Windmill tower

ABSTRACT

AN EXCEEDINGLY STABLE WINDMILL TOWER ADAPTED FOR EASE OF INSTALLATION AND OPERATION. THE STABLE WINDMILL TOWER IS ESPECIALLY ADAPTED FOR NORMALLY REQUIRED WELL SERVICING OPERATIONS INCLUDING, BUT NOT LIMITED TO, REMOVING THE WINDMILL FROM OVERLYING RELATIONSHIP TO THE CONCENTRIC WELL CASING, WELL PIPE, AND THE PUMPING ROD, BY ROTATING THE WINDMILL TOWER ABOUT ITS VERTICAL AXIS FROMK GROUND LEVEL BY THE OPERATOR.

Feb. 9, 1971 M. A. PETERSON 3,561,890

WINDMILL TOWER Filed June 5, 1969 3 Sheets-Sheet 1 lOl 3 63 fi /[FRY f51 o 60R 74 I 6; GI

MART/IV A. PETERSON ATTOR N EY BY k Feb. 9, 1971 M. A. PETERSON3,561,890

WINDMILL TOWER Filed June 5, 1969 3 Sheets-Sheet 2 MART/N A. PETERSONINVENTOR.

By ATTORNEY Feb. 9, 1971 M. A. PETERSON WINDMILL TOWER 3 SheetsShee t 5Filed June a, 1969 MART/N A. PETERSON mvamoa BY )ZwM my ATTORNEY3,561,890 WINDMILL TOWER Martin A. Peterson, Newport, Nebr. (RED. 1,Rose, Nebr. 68772) Filed June 5, 1969, Ser. No. 830,675 Int. Cl. F04!)17/00 U.S. Cl. 417-336 Claims ABSTRACT OF THE DISCLOSURE An exceedinglystable windmill tower adapted for ease of installation and operation.The stable windmill tower is especially adapted for normally requiredwell servicing operations including, but not limited to, removing thewindmill from overlying relationship to the concentric well casing, wellpipe, and the pumping rod, by rotating the windmill tower about itsvertical axis from ground level by the operator.

Windmill towers conventionally comprise an upright mast or standard, theupper portion of which is integrally provided with a substantiallyhorizontal platform that supports the wind-driven windmill loftily abovethe well casing. A vertically elongate pumping-rod is actuatablyconnected to the windmill and extends downwardly therefrom into the wellcasing along the casing-axis to a subterranean pump, rotary motion ofthe windmill blades causing vertical reciprocation of the pumping-rodwhereby subterranean water is pumped upwardly along the casing-axis tothe earth surface. In the so-called tubular well situation, the wellcasing itself serves as the vertical conduit for the upwardly pumpedfluid, while in the more prevalent concentric pipe situation, asegmented pipe concentrically surrounded by the casing serves as thevertical conduit means; in both situations the subterranean fluid ispumped upwardly along the casing-axis. Oftentimes, the subterranean pumpmal-functions whereby the pumping-rod and connected pump need to beupwardly withdrawn from the earth to permit pumping-rod and pump repair.If the well be of the concentric pipe type, both the pumping-rod and thecoupled pipe segments, i.e'. the pipe string, can be together withdrawnupwardly from the earth, to permit repair or replacement of the pump, orthe pumping-rod, or of one or more faulty pipe segments. In suchinstances, especially where the well is deep and the pumping-rod or thepipe string is lengthier than the height of the windmill above theearth, the windmill and its platform must be temporarily removed fromvertically overlying relationship with the well casing. In the priorart, such temporary removal is difficult and requires either totaldismantling of the windmill tower at ground level, or the operator mustsubject himself to the danger of climbing to the platform for therequired task.

It is accordingly the general object of the present invention to providea means for the removal of the windmill and its supporting platform fromvertical alignment with the well casing whereby said removal can besafely, readily, and conveniently accomplished from ground level, evenby a lone unassisted operator.

Other objects of the present invention are to provide a windmill towerthat is of simple and economical construction, that is exceedinglysimple to erect during original installation thereof, that is unusuallystable and reliable during operation, and that is readily and safelymain tainable in good operating condition even when it be required totemporarily remove the pumping-rod, the segmented pipe string, or thesubterranean pump from the earth.

With the above and other objects and advantages in view which willbecome more apparent as this descrip- United States Patent Ofllce3,561,890 Patented Feb. 9, 1971 tion proceeds, the windmill tower of thepresent invention generally comprises: an upright base member attachedto the earth and disposed along a vertical tower-axis that is rearwardlylaterally offset with respect to the well casing-axis; an upright loftystem disposed along the toweraxis; and adapted to rotate at least aboutthe toweraxis with respect to the base member; a novel platform memberrigidly attached to the lofty stem near the upper end thereof, saidnovel platform providing a support for a windmill disposed loftily abovethe well casing at the casing-axis; and a plurality of novel obliquebraces removably connected between the platform member and the earth.

In the drawing wherein like characters refer to like parts in theseveral views, and in which:

FIG. 1 is a side elevational view, partly broken away at the earth alongsection line 1-1 of FIG. 3, showing a preferred embodiment of thewindmill tower of the present invention.

FIG. 2 is a sectional plan view taken along line 2-2 of FIG. 1.

FIG. 3 is a top plan view taken along 3-3 of FIG. 1.

FIG. 4 is a sectional elevational view taken along lateral directionalline 44 of FIG. 3.

FIG. 5 is a sectional elevational view taken along transversedirectional line 5-5 of FIG. 3.

The environment for the windmill tower of the present invention (saidtower being indicated generally at A and having a lofty stem 20 disposedalong and rotatable about tower-axis T) includes a well W comprisingcasing 90 extending into the earth E along vertical casing-axis C to asource of subterranean water (not shown). While the present invention isequally adapted for both the tubular well and concentric pipe types wellenvironment, FIGS. 1 and 2 arbitrarily show the concentric pipe typeWell including the pipe string uppermost segment 92, the next lowersegment 91, and an inter-segments coupling 96. The uppermost pipe stringsegment 92 conventionally extends above the earth surface and maintainedthere by conventional well base cap 99, and is detachably secured to astable upright member e.g. base member 10, as by menas of laterallyextending bracket 93. A windmill having a plurality of downwardlyextending sup port legs 101 attached upon platform member 60 has apropeller or the like 102 responsive to the wind and conventional means(not shown) to translate the rotary action of propeller 102 intoreciprocatory action of the pumping-rod 105. Pumping-rod 105 is disposedalong casing-axis C and extends downwardly into the segmented pipestring, and the pumping-rod lower end is actuatably connected to a pump(not shown) at the subterranean water source whereby Water can bewithdrawn from the well through a lateral conduit or the like 94 at anydesired location. The pipe string 91-92 and the pumpingrod 105 areformed in sections or segments and may be disconnected by unscrewingcertain joints such as indicated generally at 106 on pumping-rod 105,and at 96 on the pipe string 91-92.

Windmill tower A comprises generally: a relatively short upright basemember 10 disposed along tower-axis T and afiixed to the earth as bymeans of concrete footing 15, base member upper end 11 being disposedabove the earth surface; an upright novel stem 20 extending loftilyabove base member upper end 11 and along toweraxis T, said stem 20 beingrevolvable for a least 90 about tower-axis T; a novel substantiallyhorizontal platform member 60 rigidly attached to stem 20 at stem up erend 21 and extending laterally from tower-axis T across casing-axis C,said platform 60 including hereinafter described novel attachments andfittings; and a plurality of novel oblique braces e.g. 50, 45, 46,detachably connected between the platform means and the earth E.

Upright base member preferably comprises a vertical cylindrical tubeconcentric about tower-axis T. The base member lower portion is rigidlyaffixed to the earth with concrete footing whereby base member 10 isnonrotatable about tower-axis T, and in this regard, base member 10 nearits lower end 12 has integrally attached outwardly extending lugs 13 topromote non-rotatable engagement of said base 10 into concrete footing15. Base member upper end 11 is preferably disposed less than about fourfeet above the earths surface whereby the stem lower portion immediatelyabove 11 is manipulatable by an operator of average physical height.

The upright stem herein comprises a vertical cylindrical tube concentricabout tower-axis T, stem 20 having an upper end 21 and a lower end 22.Stem upper end 21 is disposed loftily above base member upper end 11 onthe typical order of at least about ten feet whereby base member upperend 11 is disposed nearer to the earth surface than to stem upper end21. The outside diameter of stem 20 is less than the inside diameter ofbase member 10, and the stem lower portion adjacent to stem lower end 22is disposed within base member 10 below its upper end 11. Stem 20 nearerto lower end 22 than to upper end 21 integrally includes an outwardlyextending annular protuberance 23 surrounding tower-axis T, saidprotuberance 23 resting upon the upper end 11 of rigid non-rotatablebase member 10. Thus, stem 20, through protuberance 23 resting upon basemember upper end 11, is maintained in elevation above the earth and isfree to rotate about tower-axis T.

There are means, herein as set-screw 29 threadedly engaged with basemember 10 and bearable against that portion of stem 20 disposed belowbase member upper end 11, to temporarily prevent rotation of stem 20about tower-axis T. Stern 20 integrally includes a plurality ofoutwardly-extending lugs 24 along the upright height thereof to permitan operator to scale stem 20, particularly during original installationwindmill tower A. The stem upper end at 21 and above platform 60integrally includes handle means, herein as semi-circular bar 25weldably attached to stem 20, to allow suspension of stem 20 andattached platform 60 including windmill 100 from a crane during originalinstallation of windmill tower A. There is a plurality of pumping-rodguides 26 attached to stem 20 and extending laterally forwardlytherefrom for pumping-rod 105, said guides 26 being vertically openalong casing-axis C to provide a guidable lateral support forpumping-rod 105.

Substantially horizontal platform 60 is disposed on stem 20 immediatelybelow stern upper end 21 and nearer to 21 than to base member upper end11. Platform 60 has a rigidly positioned relationship to stem 20, as bymeans of abutting angle irons 65-66 and 68-69, oppose face plates 75-76and transverse bolt or pin 74, said platform 60 having a forward portion60F extending laterally forwardly of stem 20 across casing-axis Cwhereby casingaxis C is disposed between stem 20 and the platformtransverse forward end 61. There is a vertical central opening 62 in theplatform forward portion immediately below windmill 100 for passage ofvertical pumping-rod 105. Platform 60 includes a rearward portion 60Rterminating as transverse rearward end 63, said platform rearwardportion being integrally provided with transverse planking 64 to supportoperating personnel on platform 60.

A preferred type platform member as 60 is best shown in the FIG. 3 planview and in the two sectional elevational views based thereon andcomprises a pair of transversely-opposed laterally extending edges 65and 66 disposed on opposite sides of the laterally-extending verticalplane passing through axes T and C, hereinafter referred to as lateralreference plane. The platform forward portion i.e. between platformforward end 61 and axes T and C, is transversely narrower than theplatform divergent rearward portion i.e. between tower-axis T andplatform transverse rearward end 63. The peferred platform member 60 isbasically provided of rigid elongate structural material of L-shapeddual-legged cross-sectional shape i.e. angle-iron rail stock, saidelongate structural material being cut into five segments including twoidentical lengths for lateral members 65 and 66 and three identicalshorter lengths for transverse rails-spacing members 67-69. The forwardportion of lateral members 65 and 66 are parallel to each other fromplatform forward end 611 to rearwardly of tower-axis T; the upright legsof the members 65-66 opposed parallel forward portion are disposed onopposite sides of the said lateral reference plane (passing through axesT and C) and abut each opposite transverse side of stem 20 immediatelybelow stern upper end 21 whereby the horizontal legs of said membersforward portion are below stem upper end 21 and extend in oppositetransvese directions. Rails 65 and 66 rearwardly of tower-axis T andherein at third transverse rails-spacer 69 are permanently bent indivergent directions so as to support transverse planking 64 thereon.

The three transverse rails-spacing members 67-69 each intersect saidlateral reference plane and are attached as by welding between uprightlegs of rails 65 and 66. First rails-spacer member 67 is disposed atplatform forward end 61. The upright legs of second and thirdrailspacing members 68 and 69, respectively, abut the opposite lateralsides of stem 20 immediately below stem upper end 21 whereby thehorizontal legs of 68 and 69 are below stem upper end 21 and extend inopposite lateral directions. Thus, the horizontal legs of the severalmembers 65-69 are disposed along a common horizontal plane located a fewinches below stem upper end 21. The forward portions of lateral members65 and 66, together with transverse rails-spacer members 67 and 68, doprovide the vertical central opening 62 immediately below windmill 100to accommodate pumping-rod 105.

There is a pair of metallic triangular upright face plates and 76disposed on opposite transverse sides of said lateral reference plane,the said face plates 75 and 76 being attached, as by welding, to theupright legs of platform lateral arms 65 and 66, respectively. Atransverse attachment pin, herein as a threaded bolt and nut combination74, passes through face plates 75-76 and intervening stem 20 immediatelybelow members 65-66 whereby said attachment pin 74 maintains theelevation of platform member 60 immediately below stem upper end 21. Theupright leg portions of elements 65-66 and 68-69, abutting againstrespective directional sides of stem 20', prevent tilting of platformmember 60 in the lateral and transverse planes passing through toweraxis T. Thus, elements 65-66, 68-69, and 74-76, together rigidlyposition the relationship between platform 60 and stem 20.

One of the platform lateral edges, herein along rail 66, is providedwith a vetrically open annular collar 72 positioned transverselyperpendicularly alongside casing-axis C and pumping-rod 105, said collar72 being attached as by welding to a notch in the horizontal leg of rail66. The inside diameter of collar 72 exceeds the outside diameter ofeach pipe string segment eg, 92, 91, etc. The transverse distance of thecollar 72 central opening from the lateral reference plane is less thanabout six inches per ten feet of the collar 72 height above the earthssur face when steel pipe segments 91, 92, having a diameter of less thantwo inches, is employed. There are blockand-tackle attachment means,herein as transversely open lug or ear 71, attached as by welding to theupright leg of lateral rail 66, transversely" alongside collar 72.

Windmill is attached upon platform 60 at the upper end of pumping-rod asby means of four upright brackets 41, each of said brackets 41 extendingintegrally uprightly from platform forward portion 60F and convergingtoward tower-axis T above platform 60. Specifically herein, each of thefour upright brackets 41 is cut to substantially identical lengths fromangle-iron stock similar to that for elements 65-69, but ofdimensionally smaller cross-sectional size, two of the brackets 41 beingatttached as by welding to first rail 65 and two brackets 41 beingsimilarly attached to second rail 66. Each of the upwardly convergentbrackets 41 uprightly abuts and is attached to, as by bolting, to atrespective upwardly convergent support-leg 101 of windmill tower r100.

Windmill tower A includes as stabilizing means a plurality of obliquebraces connected to the platform member, each of said braces extendingdownwardly from the platform obliquely to tower-axis T and beingremovably attached to the earth. The said plurality of oblique bracespreferably takes the form of a novel rigid ladder 50 comprising a pairof upwardly-converging rigid side members 55 and 56 connected togetherwith a plurality of rigid horizontal transverse rungs 54; theside-member oblique braces 55 and 56 are each attached to platform 60 atseparate stations on the platform rearward end 63 and extend obliquelydownwardly from platform rearward end 63 to the earth. Specifically, therespective upper ends of ladder side-members braces 55 and 56 at ladderupperfonward end 51 is each provided with an attached I-I- shapedbracket 53 whereby a bifurcate clevis is provided on the upper-forwardend of the respective side-members 55 and 56. The upright legs of therespective rails 65 and 66 at platform rearward end 63 fit between thebifurcate clevis of the respective bracket 53, and a transverse pivotpin 57 is employed with each bracket 53 to pivotably attach firstside-member brace 55 to first platform rail 65 and to pivotably attachsecond side-member brace 56 to second platform rail 66. Ladderside-members 55 and 56 are downwardly divergent whereby the spacing ofsidemembers 55 and 56 at ladder lower end 52 is dimensionally greaterthan at ladder upper end 51. There is a pair of upright ground-stakes 58firmly implanted into the earth at ladder lower end 52, transverse pivotpins 59 being employed to removably attach the respective sidememberbraces 55 and 56 to separate ground-stakes 58.

Additional oblique-bracing stabilization means are advantageouslyemployed at platform forward end 61 in the event that a relatively largesize windmill 100 is to be carried atop platform 60. For example,platform 60 at platform forward end 61 might carry an eye-bolt 47attached as by welding to one or both of platform rails 65 and 66. Anelongate cable guy-wire e.g. 45, 46, is attached to platform 60 as bymeans of an eye-bolt 47, each respective guy-wire extending obliquelydownwardly and forwardly of platform 60 and being removably attached tothe earth as by means of eye-bolt type groundstakes 48. If two or moreguy-wire stabilization means are employed, they should be non-paralleland downwardly-divergent as shown herein with guy-wire elements 45 and46.

Typical erection and installation of the windmill tower A of the presentinvention, including pumping-rod 105 along casing-axis C, is as follows.First, a hole is excavated into the earth E rearwardly of casing-axis C,and base member is permanently vertically implanted into the earth bypouring concrete into the excavation and around the lower portions ofbase member 10 including at base member lower end 12 and at lugs 13.After the concrete footing 15 has hardened to secure base member 10along vertical tower-axis T, stem is laid horizontally upon the earthand platform 60 together with attached windmill 100 is attached to thestem upper portion 21 utilizing face plates 75-76 and attachement pin74. Then, stem 20 is vertically suspended at handle means from a loftyportable crane mechanism (not shown), and the stern tower portionbetween stem lower end 21 and stem protuberance 23 is inserted into thebase member 10 commencing downwardly from base member upper end 11whereby stem protuberance 23 rests upon base member upper end 11 tomaintain stem upper end 21 and platform 60 a lofty distance above theearth. Then, the installer ascends stem 20 utilizing stem lugs 24 toarrive at platform 60 whereupon oblique braces 45, 46

and 50, can be installed, the heavier element 50 being simultaneouslycarried to platform level with the said crane means. Pumping-rod is fedupwardly through vertically-open guides 26 by personnel at ground level,and the installer atop platform 60 operatively attaches pumping-rod 105to the windmill 100. Finally, at ground level, the oblique braces e.g.50, 45, 46, are removably attached to the earth as previously indicated.

Operation of the windmill tower A in the typical servicing situationwhere pipe string 91-92 or pumping-rod 105 is to be upwardly withdrawnfrom well W is as follows. In the case of shallow wells (of less thanabout feet in depth and the pipe string is of relatively small diameterand transversely resiliently bendable), a conventionally manuallyoperable block-and-tackle is removably suspended from lug 71 and thepipe string and disconnected pumping-rod 105 are pulled upwardly there-With, said casing being guided upwardly through transversely offsetcollar 72. However, in the particular case of deep wells (of greaterdepth than about 150 feet), where a transportable crane is used toupwardly withdraw the pipe string from the well, it is first necessarythat upright stem 20 be rotated at least 90 about toweraxis T in orderthat the platform member be removed from the locus of tower-axis T asindicated in phantom line in FIG. 3. In such instance, stem 20 is firstrotationally freed with respect to base member '10 as by release of theset screw or similar means 29. Then, the oblique brace means e.g. 45,56, 50, are temporarily freed from the earth, as by removal of pins 59,or by uncoupling of guy-wires 45-46 from their earth connectors 48. Inthe case of a relatively short stem 20, and a short base member 10, stem20 can be rotated the required 90 about tower-axis T, simply by the useof a pipe wrench applied to stem 20 by an operator standing alongsidebase member 10, However, in the case of more massive stem and basemembers, the operator may manually grasp the ladder-side members 55-56at ladder lower end 52, thus employing oblique ladder 50 as a lever tocause rotation of stem 20 and associated platform 60 about tower-axis T.The novel ladder 50 not only functions advantageously as aforesaid foroblique bracings and as a lever for rotating stem 20, but its obliquenature further provides an exceedingly convenient means for ascending toplatform 60 at planking 64, much safter to use than the steep uprightlugged stem 20, 24.

From the foregoing, the construction and operation of the windmill towerwill be readily understood and further explanation is believed to beunnecessary. However, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction shown and described, andaccordingly, all suitable modifications and equivalents may be resortedto, falling within the scope of the appended claims.

I claim:

1. A windmill tower for operating and servicing a well having an uprightcasing extending deeply into the earth along a vertical casing-axis anda subterranean pump for upwardly withdrawing water therefrom, saidwindmill tower comprising:

(A) An upright base member attached to the earth and disposed along avertical tower-axis, said toweraxis being substantially parallel to thecasing-axis and laterally rearwardly offset therefrom for a finitedistance, said base member having an upper end disposed above the earthsurface;

(B) An upright lofty stem disposed along said toweraxis and extendingloftily above the base member upper end and including a stem upper end,said stern being rotatably secured to the base member above the earthwhereby the stem is adapted to turn at least about 90 about saidvertical tower-axis;

(C) A substantially horizontal platform member attached to the stern anddisposed on said lofty stem nearer to the stem upper end than to thebase mem ber upper end, said platform member having a forward portionextending laterally forwardly of the upright stem to intersect thevertical casing-axis whereby the casing-axis is disposed between theplatfrom transverse forward end and the tower-axis, said platform havinga rearward portion including a transverse rearward end positionedrearwardly of the tower-axis, said platform member including a windmillsupported upon the platform forward portion, and a lofty verticalpumping-rod disposed along the casing-axis and operatively connectedbetween the windmill and the subterranean pump; and (D) A plurality ofoblique braces connected to the said platform member, each of saidbraces extending downwardly from the platform obliquely to thetower-axis and removably attached to the earth.

2. The windmill tower of claim '1 wherein the base member at the upperend is cylindrically tubular and is concentric about the tower-axis,said base member lower portion at the earth surface being rigidlyaffixed within a concrete slab whereby the base member is non-rotatableabout the tower-axis; and wherein the upright stem is of cylindricaltubular shape along the upright height thereof between the stem upperand lower ends, said stem lower portion extending downwardly into thebase member tubular upper portion and including an outward protuberanceresting upon the base member upper end whereby the stem is maintained inelevation above the earth and is rotatable about the tower-axis.

3. The windmill tower of claim 2 wherein the upright stem above the basemember upper end integrally includes outwardly extending lugs to permitan operator to climb upwardly along the stem to the platform member;wherein the plurality of oblique braces comprises a substantially rigidladder having a pair of rigid oblique side-members connected togetherwith a plurality of rigid transverse rungs, the upper ends of the ladderside-members being each pivotably connected to the platform rearwardportion with transverse pivot pins and the lower ends of the ladderside-members being disposed rearwardly of the ladder side-members upperends and above the earth surface, the lower end of each of the ladderside-members being removably attached to a ground stage; and whereinthere are means connected between the stem lower portion and the basemember to temporarily prevent rotation of the stem about the tower-axis.

4. The windmill tower of claim 3 wherein there is a handle meansattached to the stern and extending above the stem upper end and abovethe platform member for suspending the stem and the attached platformmember from a crane during original installation of the windmill tower;and wherein the plurality of oblique braces further comprise at leastone cable attached to the platform forward portion and extendingdownwardly and forwardly from the platform forward end, the lower end ofsaid at least one cable being removably attached to the earth.

5. The windmill tower of claim 1 wherein the platform member has a pairof transversely-opposed laterally-extending edges disposed on oppositesides of the laterallyextending vertical plane passing through thetower-axis and the casing-axis, said platform member integrallyincluding a vertically open collar disposed transversely of thecasing-axis, said platform member further including a block-and-tackleattachment means disposed substantially immediately below the verticallyopen collar; and wherein the windmill has a plurality of downwardlyextending lofty support legs of rectangular horizontal crosssection,said platform member forward side integrally includingupwardly-extending lofty brackets of L-shaped horizontal cross-sectionabutting against two of the lofty sides of each of the windmillsupport-legs.

6. The windmill tower of claim 5 wherein the two transversely-opposedlaterally-extending edges of the platform member at the rearward portionthereof diverge from each other whereby the platfom transverse rearwardend is wider than the platform transverse forward end; and wherein theplatform member rearward portion is provided with attached transverseplanks to support an operator upon the platform.

7. The windmill tower of claim 6 wherein the base member at the upperend is cylindrically tubular and is concentric about the tower-axis,said base member lower portion at the earth surface being rigidlyaffixed within a concrete slab whereby the base member is non-rotatableabout the tower-axis; and wherein the upright stem is of cylindricaltubular shape along the upright height thereof between the stem upperand lower ends, said stem lower portion extending downwardly into thebase member tubular upper portion and including an outward protuberanceresting upon the base member upper end whereby the stem is elevatedabove the earth and is rotatable about the tower-axis.

8. The windmill tower of claim 7 wherein the upright stem above the basemember upper end integrally includes outwardly extending lugs to permitan operator to climb upwardly along the stem to the platform member;wherein the plurality of oblique braces comprises a substantially rigidladder having a pair of rigid upwardlyconverging oblique side-membersconnected together with a plurality of rigid transverse rungs, the upperends of the ladder side-members being each pivotably connected to theplatform rearward portion with transverse pivot pins and the lower endsof the ladder side-members being disposed rearwardly of the ladderside-members upper ends and above the earth surface, the lower end ofeach of the ladder side-members being removably attached to a groundstake; and wherein there are set screw means connected between the stemlower portion and the base member to temporarily prevent rotation of thestem about the tower-axis.

9. The windmill tower of claim 8 wherein there is semi-circular handlemeans attached to the stem upper end and disposed above the platformmember for suspending the stem and the attached platform member from acrane during original installation of the windmill tower; and whereinthe plurality of oblique braces further cornprises at least one cableattached to the platform forward end and extending downwardly andforwardly from the platform forward end, the lower end of said at leastone cable being removably attached to the earth.

1-0. The windmill tower of claim 6 wherein the two laterally-extendingsides of the platform comprise single lengths of metallic rail stockincluding parallel forward portions of each rail and divergent rearwardportions of each rail, the stem upper end fitting snugly between theparallel forward portions of the opposed lateral rails and between apair of transverse rail-spacers on respective lateral sides of thetower-axis, each of said opposed rails having an attachedlaterally-extending face plate, said opposed face plates and interveningstem being pierced I by a transverse attachment pin.

References Cited UNITED STATES PATENTS 419,526 1/1890 Keep 103-593,099,220 7/1963 Butman 10358 ROBERT M. WALKER, Primary Examiner

